66 kV CIRCUIT BREAKER (OUTDOOR TYPE)

66 kV Circuit Breakers shall be outdoor
type, comprising three identical single pole units, complete in all respects
with all fittings and wiring. The circuit breakers and accessories shall
conform to IEC-62271-100 or equivalent Indian Standard.

2. DUTY
REQUIREMENTS

2.1 Circuit breaker shall be suitable for 3
phase, 50 Hz, 66 kV System. The circuit breaker shall meet the duty requirement
of any type of fault or fault location, when used on 66 kV effectively grounded
or ungrounded systems and perform make and break operations as per the
stipulated duty cycles satisfactorily.

2.2 The rated transient recovery voltage
for terminal fault and short line faults shall be as per IEC:62271-100.

2.3 The circuit breakers shall be
reasonably quiet in operation. Noise level in excess of 140 dB measured at base
of the breaker would be unacceptable. Bidder shall indicate the noise level of
breaker at distance of 50 to 150 m from base of the breaker.

2.4 The Bidder may note that total break
time of the breaker shall not be exceeded under any duty conditions specified
such as with the combined variation of the trip coil voltage, pneumatic
pressure and arc extinguishing medium pressure, etc.

2.5 While furnishing particulars regarding
the D.C. component of the circuit breaker, the Bidder shall note that
IEC-62271-100 requires that this value should correspond to the guaranteed
minimum opening time under any condition of operation.

2.6 The critical current which gives the
longest arc duration at lock out pressure of extinguishing medium and the
duration shall be indicated.

2.7 All the duty requirements specified above
shall be provided with the support of adequate test reports to be furnished
along with the bid.

31.5 kA with
percentage of DC component as per IEC56 corresponding to
minimum opening time under
operating conditions specified

6

Symmetrical interrupting Capability

31.5 kA rms

7

Short time current carrying Capability

31.5 kA rms for one (1) second

8

Rated normal current in amps.

800A (utility
to customize based on actual requirement)

9

Total break (opening time)

60 m sec. (3 cycles)

10

Reclosing

Three phase high speed auto reclosing (as required)

11

Total closing time

100 ms

12

Trip and closing coil voltage

As per substation D.C. Voltage

13

Auxiliary contacts

As required plus 8NO and 8NC contacts per pole as spare. The
contacts shall have continuous rating
of 10A and
breaking capacity of 2A with circuit time constant of minimum 20
millisecond at 220V DC (Typ.)

14

Temperature rise over Ambient

As per IEC:62271-100

15

Type of operating mechanism

Spring charging

16

Rated ambient temperature

50 deg. Centigrade

17

Seismic acceleration

0.3g horizontal

18

Rated voltage

66 kV (rms)

19

Rated one minute power frequency withstand voltage (Dry and Wet)

170 kV rms

20

Rated lightning impulse withstand voltage (1.2/50 Micro-Sec.)

325 kVp

21

No. of Terminals in common control cabinet

All contacts to be wired to common control cabinet with 24 extra
terminal blocks.

4. CONSTRUCTIONAL FEATURES

4.1 All
making and breaking contacts shall be sealed and free from atmospheric effect.
In the event of leakage of extinguishing medium to a value, which cannot
withstand the dielectric stresses specified in the open position, the contacts
shall preferably self-close. Main contacts shall be first to close and the last
to open and shall be easily accessible for inspection and replacement. If there
are no separately mounted arcing contacts, then the main contacts shall be
easily accessible for inspection and replacement. Main contacts shall have
ample area and contact pressure for carrying the rated current under all
conditions. The interrupter sectional drawing showing the following conditions
shall be furnished for information with the bid:

a)
Close
position

b) Arc
initiation position

c) Full arcing position

d) Arc
extinction position

e) Open
position.

4.2 All
the three poles of the breaker shall be linked together electrically.

4.3 Circuit
breakers shall be provided with two (2) independent trip coils, suitable for
trip circuit supervision. The trip circuit supervision relay would also be
provided. Necessary terminals shall be provided in the central control cabinet
of the circuit breaker.

6.2 The
operating mechanism shall be anti-pumping and trip free (as per IEC definition)
electrically and either mechanically or pneumatically under every method of
closing. The mechanism of the breaker shall be such that the position of the
breaker is maintained even after the leakage of operating media and/or gas.

6.3 The
operating mechanism shall be such that the failure of any auxiliary spring will
not prevent tripping and will not cause trip or closing operation of the power
operated closing devices. A mechanical indicator shall be provided to show open
and close positions of breaker. It shall be located in a position where it will
be visible to a man standing on the ground with the mechanism housing door
closed. An operation counter shall also be provided.

6.4 Closing
coil shall operate correctly at all values of voltage between 85% and 110% of
the rated voltage. Shunt trip coils shall operate correctly under all operating
conditions of the circuit breaker upto the rated breaking capacity of the
circuit breaker and at all values of supply voltage between 70% and 110% of
rated voltage. If additional elements are introduced in the trip coil circuit
their successful operation for similar applications of outdoor breaker shall be
clearly brought out in the bid.

6.5 Working
parts of the mechanism shall be of corrosion resisting material. Bearings
requiring grease, shall be equipped with pressure type grease fittings. Bearing
pin, bolts, nuts and other parts shall be adequately pinned or locked to
prevent loosening or changing adjustment with repeated operation of the
breaker.

6.6 Operating
mechanism shall normally be operated by remote electrical control. Electrical
tripping shall be performed by shunt trip coil. Provision shall also be made
for local electrical control. ‘Local/remote’ selector switches and closes &
trip push buttons shall be provided in the breaker central control cabinet.
Remote located push buttons and indicating lamps shall also be provided.

6.7 Operating
mechanism and all accessories shall be in local control cabinet. A central
control cabinet for the three poles of the breaker shall be provided along with
supply of necessary tubing, cables, etc.

6.8 Provisions
shall be made on breakers for attaching an operation analyser to perform speed
tests after installation at site to record contact travel against time and
measure opening time.

6.9 The
Bidder shall furnish curve supported by test data indicating the opening time
under close-open operation with combined variation of trip coil and operating
media along with the bid.

6.10 Spring
Operated Mechanism

Spring operated mechanism shall be
complete with motor, opening spring & closing spring with limit switch for
automatic charging and other necessary accessories to make the mechanism a
complete operating unit. Opening spring shall be supplied with limit switch for
automatic charging and other necessary accessories.

As long as power is available to the
motor, a continuous sequence of closing and opening operations shall be
possible. The motor shall have adequate thermal rating for this duty. After
failure of power supply to the motor, one close-open operation shall be
possible with the energy contained in the operating mechanism.

Breaker operation shall be independent
of the motor, which shall be used solely for compressing the closing spring.

Motor ratings shall be such
that it requires not more than 30 seconds for fully charging the closing
spring.

When closing springs are discharged,
after closing a breaker, closing springs shall automatically be charged for the
next operation and an indication of this shall be provided in the local and
remote control cabinet.

The spring operating mechanism shall
have adequate energy stored in the operating spring to close and latch the
circuit breaker against the rated making current and also to provide the
required energy for the tripping mechanism in case the tripping energy is
derived from the operating mechanism.

6.11 Fittings and Accessories

6.11.1 Following is list of some of the major
fittings and accessories to be furnished as integral part of the breakers.
Number and exact location of these parts shall be indicated in the bid.

6.11.2 Control unit/Central control cabinet shall
be complete with:

a) Double
compression type cable glands, lugs, ferrules, etc.

b) Local/remote changeover switch

c) Operation counter

d) Fuses, as required

e) Anti-pumping relay/contactor

g)Rating
and diagram plate in accordance with IEC including year of manufacture, etc.

Any
fittings, accessories or apparatus which may not have been specifically
mentioned in this specification but which are usually necessary for the
satisfactory operation of the equipment, shall be deemed to have been included
in this specification.

10. PACKINGS:

All
material shall be suitably packed for transport, direct to site and
Manufacturer shall be responsible for all damages/losses due to improper
packing. All boxes shall be marked with signs indicating the up and down sides
of the boxes along with the unpacking instructions, if considered necessary by
the Manufacturers.